Rotary power lawn mowers have been manufactured for many years. Their usefulness is well-known and their usage is widespread. Also known, unfortunately, are the still existing hazards inherent with the use of rotary power mowers, namely the ever present danger of accidents and possible injuries to an operator.
The whirling blade of a rotary power mower becomes potentially dangerous when the operator for any reason leaves his normal position behind the mower or other persons, especially children, are near the mower.
Innumerable attempts have been made to develop a safe and reliable mechanism to minimize and preferably eliminate the causes responsible for the unnecessary and sometimes tragic accidents, mishaps and injuries.
One of the improvements contained in the present invention is directed to an articulated clutch shoe which makes it possible to generate greater force while using smaller flyweights because this shoe can exert greater leverage from the centrifugal force acting on the flyweight.
This invention provides an improved combination of a clutch and brake mechanism which automatically disengages the source of prime power supply, such as an engine, from the cutting blade and simultaneously applies positive braking that stops the whirling blade whenever the mower handle is released intentionally or inadvertently.
The importance and significance of this invention becomes more apparent and can better be appreciated when it is realized that the blade control handle is predisposed to be in the blade stopping position under various predictable circumstances; e.g. when the operator is busy starting the mower engine, is removing the grass catcher to empty it or attach it back to the mower, is clearing debris, such as sticks from the vicinity of the mower or is adjusting cutting heights, etc. Additionally, when a child approaches the mower, when the mower is pushed across a gravel driveway or when any other hazardous condition arises, the blade is stopped by simple release of the blade control handle. There are numerous recorded accidents which have occurred under these and other circumstances.
During the occasion of any of the aforementioned events, it is of paramount importance for obvious reasons of safety that two events take place simultaneously and instantly to insure against injury: (1) that the mower blade be disengaged at once from its source of power and (2) that it be stopped positively at once and be held immobile.
Such safe operation is achieved through the use of this improved combination of clutching and braking mechanism which disconnects the power supply from the mower blade while at the same time engages a positive braking mechanism whenever the blade control handle is not in its normal operation position. Conversely, this invention releases the brake and engages the clutching mechanism whenever the blade control handle is moved to its normal operating position.
It is an object of this invention to provide on a rotary power mower effective, foolproof and convenient means for disengaging the blade from its driving power source.
It is another object of this invention to provide safe, effective and reliable braking means for stopping the mower blade in a positive manner.
It is still another object of this invention to provide means for stopping the mower blade by automatically and simultaneously disengaging a clutching mechanism while engaging a braking mechanism.
It is still another object of this invention to stop the rotating blade of the mower by disengaging a friction type clutch mechanism while at the same time engaging a braking mechanism when a dead man control is released.
It is further another object of this invention to stop the rotating blade of a power mower by disengaging the friction type clutch mechanism and engaging a braking mechanism within a time span ranging from 1 to 3 seconds from the moment the dead man control mechanism is released.
It is still another object of this invention to disengage the power source of the mower from the blade and to stop the blade by means of greatly improved and highly reliable clutch and brake designs.
It is still another object of this invention to use a new design of an articulated clutch shoe to provide a better distribution of forces on the clutch drum assembly, thus resulting in reduced stress in the friction material of the drum with less wear.
It is still another object of this invention to automatically disengage the blade when cutting is too heavy for the engine and thereby prevent engine stall.
Another object of this invention is an improved clutching mechanism design to improve the stress distribution in the clutch through the use of a hub member in the clutch assembly.
Still another object of this invention is a new and improved clutch mechanism which includes a friction member which is both cylindrical and cone-shaped on the outside and hexagonally shaped on the inside.
Still another object of this invention is to provide a new concept in clutch shoe and friction drum design which substantially improves the life of the clutch, improves dissipation of heat and simplifies construction.
It is another object of this invention to provide the clutch mechanism with unlined counterweighted clutch shoes which pivot about shoulder bolts.
It is still another object of this invention to provide shouldered bolts in the blade retaining assembly to insure that the clamp load of the blade fastening nuts do not distort the clutch or brake components. These shoulder bolts also serve as pivots for the flyweight clutch shoes, transmit engine torque from the flyweights to the blade and help transmit braking torque from the brake disc to the blade.